Detecting Barriers to Gene Flow Among Extinct Populations

The Arctic is the most susceptible of Earth’s ecosystems to climate change. Over the last million or so years, the Arctic has seen multiple, dramatic oscillations between cold, glacial periods and warm interglacial periods, some of which were similar in magnitude to present-day climate change. These shifts in temperature and precipitation patterns, along with more recent anthropogenic influences, redistribute habitat and change barriers to gene flow, resulting in both local and global extinctions. Demographic changes, including range shifts and periods of population growth or decline, are recorded in the genomes of the plants and animals that made up these ancient arctic communities. Drawing from genomic data isolated from horses and steppe bison that lived in the Klondike region of the Yukon Territory over the last 700,000 years, I will describe the rise and fall, and rise and fall, and eventual extinction of these two, at-times-abundant, iconic, ice-age species. I will show how each species responded individualistically to the changing arctic climate, and highlight the power of paleogenomics, despite its many challenges and limitations, to reveal complex patterns of demographic change over hundreds of thousands of years of evolutionary history.